A Highly Linear Overmodulation Method for Dual Inverter with an Isolated DC Bus Considering Phase Voltage and Current THD Reduction

This paper introduces an overmodulation strategy designed to reduce the total harmonic distortion (THD) of phase voltages and currents in a dual-inverter with an isolated DC Bus system. Under conventional overmodulation control, the clamping of output voltage reference vectors in the primary and secondary inverters contributes to THD degradation of the phase voltages and currents. Aiming to address this issue, the proposed technique minimizes the clamping interval by optimally allocating the modulation indexes of the voltage reference vectors between the two inverters. Therefore, voltage utilization is maintained while harmonic distortion is reduced. The effectiveness of the proposed method is validated through experimental results.